Vehicle air conditioning control systems

ABSTRACT

An air conditioning system of a vehicle having an internal combustion engine includes a condenser configured to receive refrigerant output by an electric compressor and transfer heat from the refrigerant within the condenser to air passing the condenser. A first evaporator is configured to receive refrigerant from the condenser when a first control valve is open and transfer heat from air passing the first evaporator to the refrigerant within the first evaporator. A first blower is configured to blow air across the first evaporator to a first section of a cabin of the vehicle. A second evaporator is configured to receive refrigerant from the condenser when a second control valve is open and transfer heat from air passing the second evaporator to the refrigerant within the second evaporator. A second blower is configured to blow air across the second evaporator to a second section of the cabin of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/563,368, filed on Sep. 26, 2017, U.S. Provisional Application No.62/563,390, filed on Sep. 26, 2017, U.S. Provisional Application No.62/563,407, filed on Sep. 26, 2017, U.S. Provisional Application No.62/563,425, filed on Sep. 26, 2017, and U.S. Provisional Application No.62/563,437, filed on Sep. 26, 2017. The entire disclosures of theapplications referenced above are incorporated herein by reference.

FIELD

The present disclosure relates to vehicles and, more particularly, toair conditioning systems of vehicles.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

Compressors may be used in a wide variety of industrial and residentialapplications to circulate refrigerant to provide a desired heating orcooling effect. For example, a compressor may be used to provide heatingand/or cooling in a refrigeration system, a heat pump system, a heating,ventilation, and air conditioning (HVAC) system, or a chiller system.These types of systems can be fixed, such as at a building or residence,or can be mobile, such as in a vehicle. Vehicles include land basedvehicles (e.g., trucks, cars, trains, etc.), water based vehicles (e.g.,boats), air based vehicles (e.g., airplanes), and vehicles that operateover a combination of more than one of land, water, and air.

A vehicle typically includes an HVAC system that heats and cools adriving area of the vehicle where a driver sits. Some vehicles, such assemi-trucks, also include a living area where a driver can sit, sleep,rest, etc. Some vehicles may include a partition (e.g., curtain or wall)that can be opened to join the driving area and the living area. Thepartition can also be closed to separate the driving and living areas,for example, for sleeping.

Typically, compressors of HVAC systems of vehicles are engine driven.Thus, the engine is on to provide cooling. As such, in addition torunning during movement of the vehicle, the engine of the vehicle staysrunning to provide cooling while the driver is sleeping and at othertimes when the vehicle is not moving.

SUMMARY

In a feature, an air conditioning system of a vehicle having an internalcombustion engine is described. A condenser is configured to receiverefrigerant output by an electric compressor and transfers heat from therefrigerant within the condenser to air passing the condenser. A firstevaporator is configured to receive refrigerant from the condenser whena first control valve is open and transfers heat from air passing thefirst evaporator to the refrigerant within the first evaporator. A firstblower is configured to blow air across the first evaporator to a firstsection of a cabin of the vehicle. A second evaporator is configured toreceive refrigerant from the condenser when a second control valve isopen and transfers heat from air passing the second evaporator to therefrigerant within the second evaporator. A second blower is configuredto blow air across the second evaporator to a second section of thecabin of the vehicle. A control module is configured to open the firstcontrol valve and start operation of the electric compressor when theinternal combustion engine of the vehicle is on and the first blower isblowing air across the first evaporator.

In further features, the control module is further configured to openthe second control valve when the internal combustion engine of thevehicle is on and the second blower is blowing air across the secondevaporator.

In further features, an inverter drive is configured to apply power tothe electric compressor based on a compressor speed command from thecontrol module, and the control module is configured to, when theinternal combustion engine of the vehicle is on and the first blower isblowing air across the first evaporator, set the compressor speedcommand to a speed greater than zero based on a discharge pressure ofthe electric compressor.

In further features, the control module is configured to: decrease thecompressor speed command as the discharge pressure increases; andincrease the compressor speed command as the discharge pressuredecreases.

In further features, the control module is configured to determine thecompressor speed command based on the discharge pressure until atemperature of the first evaporator is less than a predeterminedtemperature, where the predetermined temperature is greater than thefreezing point temperature of water.

In further features, an inverter drive is configured to apply power tothe electric compressor based on a compressor speed command from thecontrol module, and the control module is configured to, when theinternal combustion engine of the vehicle is on and the first blower isblowing air across the first evaporator, set the compressor speedcommand to a speed greater than zero based on a present powerconsumption.

In further features, the control module is configured to: decrease thecompressor speed command as the power consumption increases; andincrease the compressor speed command as the power consumptiondecreases.

In further features, the control module is configured to determine thecompressor speed command based on the power consumption until atemperature of the first evaporator is less than a predeterminedtemperature, and the predetermined temperature is greater than thefreezing point temperature of water.

In further features, an inverter drive is configured to apply power tothe electric compressor based on a compressor speed command from thecontrol module, and the control module is configured to, when theinternal combustion engine of the vehicle is on and the first blower isblowing air across the first evaporator, set the compressor speedcommand to a speed greater than zero based on a discharge pressure ofthe electric compressor and a present power consumption.

In further features, the control module is configured to: decrease thecompressor speed command when at least one of: the power consumptionincreases; and the discharge pressure increases; increase the compressorspeed command when at least one of: the power consumption decreases; andthe discharge pressure decreases.

In a feature, an air conditioning control method for a vehicle having aninternal combustion engine includes: determining whether the internalcombustion engine of the vehicle is on; determining whether a firstblower of the vehicle is blowing air across a first evaporator, wherethe first evaporator is configured to receive refrigerant from acondenser when a first control valve is open and to transfer heat fromair passing the first evaporator to the refrigerant within the firstevaporator, where the first blower is configured to blow air across thefirst evaporator to a first section of a cabin of the vehicle, and wherethe condenser is configured to receive refrigerant output by an electriccompressor and to transfer heat from the refrigerant within thecondenser to air passing the condenser; and, when the internalcombustion engine of the vehicle is on and the first blower is blowingair across the first evaporator, opening the first control valve andstarting operation of the electric compressor, where a second evaporatoris configured to receive refrigerant from the condenser when a secondcontrol valve is open and to transfer heat from air passing the secondevaporator to the refrigerant within the second evaporator, and where asecond blower is configured to blow air across the second evaporator toa second section of the cabin of the vehicle.

In further features, the air conditioning control method furtherincludes opening the second control valve when the internal combustionengine of the vehicle is on and the second blower is blowing air acrossthe second evaporator.

In further features, the air conditioning control method furtherincludes: applying power to the electric compressor based on acompressor speed command; and when the internal combustion engine of thevehicle is on and the first blower is blowing air across the firstevaporator, setting the compressor speed command to a speed greater thanzero based on a discharge pressure of the electric compressor.

In further features, the air conditioning control method furtherincludes: decreasing the compressor speed command as the dischargepressure increases; and increasing the compressor speed command as thedischarge pressure decreases.

In further features, the air conditioning control method furtherincludes determining the compressor speed command based on the dischargepressure until a temperature of the first evaporator is less than apredetermined temperature, where the predetermined temperature isgreater than the freezing point temperature of water.

In further features, the air conditioning control method furtherincludes: by an inverter drive, applying power to the electriccompressor based on a compressor speed command; and when the internalcombustion engine of the vehicle is on and the first blower is blowingair across the first evaporator, setting the compressor speed command toa speed greater than zero based on a present power consumption.

In further features, the air conditioning control method furtherincludes: decreasing the compressor speed command as the powerconsumption increases; and increasing the compressor speed command asthe power consumption decreases.

In further features, the air conditioning control method furtherincludes determining the compressor speed command based on the powerconsumption until a temperature of the first evaporator is less than apredetermined temperature, where the predetermined temperature isgreater than the freezing point temperature of water.

In further features, the air conditioning control method furtherincludes: by an inverter drive, applying power to the electriccompressor based on a compressor speed command; and when the internalcombustion engine of the vehicle is on and the first blower is blowingair across the first evaporator, setting the compressor speed command toa speed greater than zero based on a discharge pressure of the electriccompressor and a present power consumption.

In further features, the air conditioning control method furtherincludes: decreasing the compressor speed command when at least one of:the power consumption increases; and the discharge pressure increases;increasing the compressor speed command when at least one of: the powerconsumption decreases; and the discharge pressure decreases.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIGS. 1A and 1B are functional block diagrams of example vehiclesystems.

FIG. 2 includes an example illustration of an example vehicle includingcomponents of an air conditioning system.

FIG. 3 includes a functional block diagram of an example implementationof the air conditioning system.

FIG. 4 includes a functional block diagram of an example systemincluding a control module, various sensors of the vehicle, and variousactuators of the vehicle.

FIG. 5 includes a functional block diagram of an example implementationof the control module.

FIG. 6 includes a flowchart depicting an example method of controllingthe speed of a compressor for pulldown.

FIG. 7 includes an example graph of compressor speed command adjustmentvalues as a function of discharge pressure.

FIG. 8 includes an example graph of compressor speed command adjustmentvalues as a function of power consumption.

FIGS. 9A and 9B include a flowchart depicting an example method ofcontrolling the speed of a compressor based on an evaporator temperaturefor pulldown and preventing freezing at the evaporator heat exchanger(HEX).

FIG. 10 includes an example graph of compressor speed command adjustmentvalues as a function of evaporator temperature.

FIGS. 11A and 11B include a flowchart depicting an example method ofcontrolling the speed of a compressor based on an evaporator temperatureand a suction pressure for pulldown and preventing freezing at theevaporator HEX.

FIG. 12 includes an example graph of compressor speed command adjustmentvalues as a function of suction pressure.

FIG. 13 includes a flowchart depicting an example method of controllingthe speed of a compressor based on discharge pressure.

FIG. 14 includes a flowchart depicting an example method of controllingthe speed of a compressor based on power consumption of the airconditioning system.

FIG. 15 includes a flowchart depicting an example method of controllingthe speed of a compressor and the speed of a condenser fan.

FIGS. 16, 17, and 18 include example graphs of condenser fan speedcommands as functions of power consumption, discharge pressure, andcompressor speed, respectively, for when the engine is on.

FIGS. 19A and 19B include a flowchart depicting an example method ofcontrolling the speed of a compressor to manage charge of a battery packwhile the engine is off.

FIG. 20 includes an example graph of compressor speed command adjustmentvalues as a function of blower speeds.

FIG. 21 includes a flowchart depicting an example method of controllingthe speed of a compressor to manage the charge of a battery pack whilethe engine is off.

FIGS. 22, 23, and 24 include example graphs of condenser fan speedcommands as functions of power consumption, discharge pressure, andcompressor speed, respectively, for when the engine is off.

FIG. 25 includes a flowchart depicting an example method of controllinga damper door to regulate temperature of a drive.

FIG. 26A includes an example implementation of a damper door and HVACducts that can be used to cool the drive.

FIGS. 26B, 26C, 26D, and 26E include example implementations of drivefans that can be used to cool the drive.

FIG. 27 includes a flowchart depicting an example method of controllingoperation of one or more drive fans to minimize noise while the engineis off.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

Some vehicles, such as semi trucks, have a passenger cabin that has twosections: a first section where a driver drives the vehicle; and asecond section that the driver can, for example, sleep. Some vehiclesinclude heating, ventilation, and air conditioning (HVAC) systems thathave ducts that allow heating and cooling of both of the first andsecond sections.

A vehicle including an HVAC system may include a refrigerant compressor(for cooling) that is mechanically driven by the engine. The speed, andtherefore the output, of the refrigerant compressor is related to therotational speed of the engine. Because cooling is not possible when theengine is off, a driver may keep the engine running to provide cooling,even when the vehicle is parked and not being driven. For example, theengine may be kept running to provide cooling while the vehicle isparked and the driver is sleeping in the second section of the passengercabin.

Keeping the engine running to provide cooling while the vehicle isparked and the driver is sleeping is an inefficient use of the engine.Additionally, by keeping the engine running, the refrigerant compressoralso stays running and may cool the passenger cabin more than desired.

The present application involves an electric refrigerant compressor (forcooling) that is not driven by the engine. An inverter drive appliespower to the electric refrigerant compressor from a battery pack basedon a (variable) compressor speed command. A control module selectivelyvaries the compressor speed command, for example, to prevent freezing atan evaporator (e.g., based on at least one of evaporator temperature andsuction pressure), to maximize efficiency while the engine is running(e.g., based on at least one of discharge pressure and powerconsumption), and/or to maximize battery life while the engine is notrunning (e.g., based on blower speed and/or a cabin air temperature).Additionally or alternatively, the control module may selectively varycondenser fan speed and/or evaporator fan speed, for example, tomaximize efficiency while the engine is running and/or to maximizebattery life while the engine is not running.

Additionally or alternatively, the control module may selectively openan actuator (e.g., a damper door) to provide cooling to the inverterdrive when a temperature of the inverter drive becomes greater than apredetermined temperature. Cooling the inverter drive improvesefficiency of the inverter drive and may enable components having loweroperating temperature ratings to be used in the inverter drive.Components having lower operating temperature ratings may be less costlythan the same components having higher operating temperature ratings. Byusing an electric refrigerant compressor, the engine can be shut downyet the passenger cabin can still be cooled.

FIGS. 1A and 1B are functional block diagrams of example systems of avehicle 100. The vehicle 100 includes an internal combustion engine 104that combusts air and fuel within cylinders to generate propulsiontorque for the vehicle 100. The engine 104 may combust, for example,gasoline, diesel fuel, natural gas, and/or one or more other types offuel. The engine 104 outputs torque to a drivetrain 108. The drivetrain108 transfers torque to two or more wheels of the vehicle. While theexample of a semi truck is provided, the present application is alsoapplicable to other types of land based vehicles (e.g., trucks, cars,trains, busses, recreational vehicles (RVs), motor homes, etc.), waterbased vehicles (e.g., boats), air based vehicles (e.g., airplanes), andvehicles that operate over a combination of more than one of land,water, and air. Also, while the example of a wheeled vehicle isprovided, the present application is not limited to vehicles havingwheels.

An electrical source 112 is driven by the engine 104 and convertsmechanical energy of the engine 104 into electrical energy to charge abattery 116. The electrical source 112 may include an alternator, agenerator, and/or another type of device that converts mechanical energyof the engine 104 into electrical energy. While the example of a singleelectrical source is provided, multiple or zero electrical sourcesdriven by the engine 104 may be included. The electrical source 112 maybe, for example, a 12 Volt (V) alternator (e.g., in the example of FIG.1A) and/or a 48 V alternator (e.g., in the example of FIG. 1B).

The vehicle 100 also includes a battery pack 120. For example only, thebattery pack 120 may be a 48 V direct current (DC) battery pack,although another suitable battery pack may be used. The battery pack 120may include two or more individual batteries connected together or mayinclude one battery. For example, in the case of a 48 V battery pack,the battery pack 120 may include four 12 V batteries connected inseries. The batteries may be connected such that a lower voltage, suchas 12 V, 24 V, and/or 36 V can also be obtained from one, two, or threeof the batteries.

In various implementations, the battery pack 120 may include fourindividual 12 V batteries connected in series. The batteries may bearranged in two banks (A and B), each bank having two individual 12 Vbatteries (batteries 1 and 2) connected in series, to provide two 24 Vreference potentials.

The battery pack 120 supplies power to an HVAC system including an airconditioning system 124. The air conditioning system 124 selectivelycools a cooled space 128. The cooled space 128 is a space within thevehicle 100 that can be cooled based on a setpoint temperature. A driverof the vehicle drives the vehicle while located (e.g., seated at adriver's seat) within the cooled space 128. In various implementations,the cooled space 128 may be divided (e.g., physically) into multiplecooled spaces that may be cooled based on respective setpointtemperatures. For example, a driving portion 129 of the cooled space 128may be cooled based on a first setpoint temperature and a living portion131 of the cooled space 128 may be cooled based on a second setpointtemperature. The living portion 131 may be behind the driving portion129 relative to a forward direction of travel of the vehicle. The firstsetpoint temperature and the second setpoint temperature may be setaccording to user input (e.g., initiated by the driver or another user)for the first setpoint temperature and the second setpoint temperature,respectively.

A user may vary the first setpoint temperature via one or more userinput devices, such as one or more user input devices located within thedriving portion 129 of the cooled space 128. A user may vary the secondsetpoint temperature via one or more user input devices, such as one ormore user input devices located within the living portion 131 of thecooled space 128. The vehicle 100 may be for example, but not limitedto, a semi-truck that can be used to haul trailers (e.g., tractortrailers). The present application is more generally applicable tovehicles having two evaporator heat exchangers. As discussed furtherbelow, a control module may control the air conditioning system 124based on temperature(s) within the cooled space(s), set pointtemperature(s), and other parameters.

The vehicle 100 includes one or more doors, such as door 132, thatprovide access to the cooled space 128 (e.g., the driving portion 129),for example, for entry into the vehicle and exit from the vehicle. Whilethe example of only one door is shown, the vehicle 100 may include morethan one door.

As shown in the examples of FIG. 1A, the vehicle 100 may include one ormore voltage converters 150 that convert the output of the electricalsource 112 into one or more outputs for charging the battery pack 120.In the example of the electrical source 112 generating a 12 V DC output,the one or more voltage converters 150 may boost (i.e., increase) theoutput of the electrical source 112, for example, to one or more othervoltages (e.g., 24 V DC, 48 V DC) and charge the battery pack 120 viathe boosted output. Since the electrical source 112 is driven byrotation of the engine 104, the electrical source 112 may be used tocharge the battery pack 120 when the engine 104 is running.

In the example of the electrical source 112 generating a 48 V DC output,as shown in FIG. 1B, the output of the electrical source 112 may chargethe battery pack 120. The vehicle 100, however, may include a voltageconverter 152 that converts the output of the electrical source 112 intoan output for charging the battery 116, For example, the voltageconverter 152 may buck (i.e., decrease) the output of the electricalsource 112, for example, to a lower voltage (e.g., 12 V DC) and chargethe battery pack 120 via the bucked output. In various implementations,the vehicle 100 may also include a battery charger that selectivelycharges the battery 116 using received power (e.g., from the electricalsource 112 or a voltage converter).

The vehicle 100 may also include one or more battery chargers thatselectively charge the battery pack 120 using received power (e.g., fromthe electrical source 112 or a voltage converter). For example, thevehicle 100 may include four model SEC-2440 battery charger,manufactured by Samlex America Inc., of Burnaby, BC, Canada. The batterycharger may be arranged, for example, in two groups of two 24 V, 40 Abattery chargers connected to provide a 48 V, 80 A output for batterycharging. While the example of battery chargers having a 24 V, 40 Aoutput is provided, battery chargers having another output may be used,such as one 12 V charger connected to each battery. The battery chargersmay also monitor the individual batteries of the battery pack 120 andcontrol application of power to the respective batteries to preventovercharging. In various implementations, a drive (discussed furtherbelow) may charge the battery pack 120 and separate battery chargers maybe omitted.

While the electrical source 112 is shown as providing power for chargingboth the battery 116 and the battery pack 120, a second electricalsource may be used to convert power of the engine 104 into electricalpower for charging the battery pack 120. In this case, the electricalsource 112 may be used to charge the battery 116, and the secondelectrical source may be used to charge the battery pack 120.

In various implementations, the battery pack 120 may be charged via oneor more other power sources. For example, the battery pack 120 may becharged using power from a utility received via a receptacle of thevehicle. The receptacle may be configured to receive AC or DC power. Forexample, the receptacle may receive AC power from a utility via a powercord (e.g., an extension cord) connected between the receptacle and awall outlet or charger of a building. The receptacle may be, forexample, a single phase 110/120 or 208/240 V AC receptacle or a 3-phase208/240 V AC receptacle. In various implementations, the vehicle 100 mayinclude both a 110/120 V AC receptacle and a 208/240 V AC receptacle.While the example of the receptacle receiving AC power is provided, thereceptacle may alternatively receive DC power from via a power cord.Power received from a utility via a receptacle will be referred to asshore power. In this example, the vehicle 100 may include one or morebattery chargers that charge the battery pack 120 using shore power.These one or more battery chargers may be the same or different thanthose referenced above.

The vehicle 100 may optionally include a solar panel 172. The solarpanel 172 converts solar energy into electrical energy. While theexample of one solar panel is provided, multiple solar panels may beused. A voltage converter 176 converts power output by the solar panel172 and charges the battery pack 120.

As discussed further below, the air conditioning system 124 includes anelectric variable speed compressor that is not mechanically driven byany rotating component of the vehicle 100, such as the engine 104 or acomponent of the drivetrain 108. The variable speed compressor isinstead driven via electrical power applied to an electric motor of thevariable speed compressor. A control module controls operation of thevariable speed compressor to maximize comfort within the cooled space128, maximize efficiency of the air conditioning system 124, minimizedischarging of the battery pack 120, and maximize life of components ofthe air conditioning system 124.

FIG. 2 includes an example illustration of an example truck includingcomponents of the air conditioning system 124. FIG. 3 includes afunctional block diagram of an example implementation of the airconditioning system 124. In the example of FIG. 3, dotted lines indicaterefrigerant flow, and solid lines indicate electrical connections andphysical connections.

Referring now to FIGS. 2 and 3, a compressor 204 receives refrigerantvapor via a suction line of the compressor 204. In variousimplementations, the compressor 204 may receive refrigerant vapor froman accumulator that collects liquid refrigerant to minimize liquidrefrigerant flow to the compressor 204.

The compressor 204 compresses the refrigerant and provides pressurizedrefrigerant in vapor form to a condenser heat exchanger (HEX) 212. Thecompressor 204 includes an electric motor 216 that drives a pump tocompress the refrigerant. For example only, the compressor 204 mayinclude a scroll compressor, a reciprocating compressor, or another typeof refrigerant compressor. The electric motor 216 may include, forexample, an induction motor, a permanent magnet motor (brushed orbrushless), or another suitable type of electric motor. In variousimplementations, the electric motor 216 may be a brushless permanentmagnet (BPM) motor. BPM motors may be more efficient than other types ofelectric motors. The compressor 204 is a variable speed compressor.

All or a portion of the pressurized refrigerant is converted into liquidform within the condenser HEX 212. The condenser HEX 212 transfers heataway from the refrigerant, thereby cooling the refrigerant. When therefrigerant vapor is cooled to a temperature that is less than asaturation temperature of the refrigerant, the refrigerant transitionsinto liquid (or liquefied) form.

One or more condenser fans 220 may be implemented to increase airflowover, around, and/or through the condenser HEX 212 and increase the rateof heat transfer away from the refrigerant. As shown in FIG. 2, thecondenser HEX 212 may be implemented near a front of the vehicle 100such that air flows through the condenser HEX 212 when the vehicle 100is traveling in the forward direction. The condenser HEX 212, however,may be located in another suitable location.

Refrigerant from the condenser HEX 212 is delivered to a receiver 224.The receiver 224 may be implemented to store excess refrigerant. Invarious implementations, the receiver 224 may be omitted. A filter driermay be implemented to remove moisture and debris from the refrigerant.In various implementations, the filter drier may be omitted.

In various implementations, the air conditioning system 124 may includean enhanced vapor injection (EVI) system. The EVI system may expand aportion of the refrigerant from the receiver 224 to vapor form,superheat the vapor refrigerant, and provide the superheated vaporrefrigerant to the compressor 204, such as at a midpoint within acompression chamber of the compressor 204. EVI may be performed, forexample, to increase capacity and increase efficiency of the airconditioning system 124.

Refrigerant from the receiver 224 flows to a first evaporator controlvalve 244 and a second evaporator control valve 248. The firstevaporator control valve 244 may be, for example, a solenoid valve oranother suitable type of valve. The second evaporator control valve 248may be, for example, a solenoid valve or another suitable type of valve.

Before flowing to the first evaporator control valve 244 and the secondevaporator control valve 248, the refrigerant may flow through a driveHEX. The drive HEX draws heat away from a drive 256 (e.g., an inverterdrive) and transfers heat to refrigerant flowing through the drive HEX.While the example of the drive being liquid (refrigerant) cooled isprovided, liquid cooling may be omitted, and the drive 256 may be aircooled. Air cooling may be active (e.g., via one or more devices) and/orpassive (e.g., by conduction and convection). An example of activecooling of the drive 256 is discussed further below.

The drive 256 controls application of power to the electric motor 216from the battery pack 120. For example, the drive 256 may controlapplication of power to the electric motor 216 based on a compressorspeed command from a control module 260. Based on the speed command, thedrive 256 may generate three-phase AC power (e.g., 208/240 V AC) fromthe power output of the battery pack 120 and apply the three-phase ACpower to the electric motor 216. The drive 256 may set one or morecharacteristics of the three-phase AC power based on the compressorspeed command, such as frequency, voltage, and/or current. For exampleonly, the drive 256 may be a variable frequency drive (VFD). The drive256 may, for example, determine a pulse width modulation (PWM) dutycycle to apply to switches of the drive 256 to generate AC power havingthe characteristics. In various implementations, one or moreelectromagnetic interference (EMI) filters may be implemented betweenthe battery pack 120 and the drive 256.

The control module 260 may set the compressor speed command to aplurality of different possible speeds for variable speed operation ofthe electric motor 216 and the compressor 204. The control module 260and the drive 256 may communicate, for example, using RS485 Modbus oranother suitable type of communication including, but not limited to,controller area network (CAN) bus or analog signaling (e.g., 0-10Vsignals).

A high pressure cut off (HPCO) 262 may be implemented to disconnect thedrive 256 from power and disable the electric motor 216 when a pressureof refrigerant output by the compressor 204 exceeds a predeterminedpressure. The control module 260 may also control operation of thecompressor 204 based on a comparison of the pressure of refrigerantoutput by the compressor 204. For example, the control module 260 mayshut down or reduce the speed of the compressor 204 when the pressure ofrefrigerant output by the compressor 204 is less than a secondpredetermined pressure that is less than or equal to the predeterminedpressure used by the HPCO 262.

When the first evaporator control valve 244 is open, refrigerant may beexpanded to vapor form by a first expansion valve 264 and provided to afirst evaporator HEX 268. The first expansion valve 264 may include aTXV (thermal expansion valve) or may be an EXV (electronic expansionvalve).

The first evaporator HEX 268 provides cooled air to the driving portion129 of the cooled space 128. More specifically, the vapor refrigerantwithin the first evaporator HEX 268 transfers heat away (i.e., absorbsheat) from air passing through the first evaporator HEX 268. The cooledair flows from the first evaporator HEX 268 to the driving portion 129of the vehicle 100 via first HVAC ducts 270. The first HVAC ducts 270include at least one duct through which cooled air flows to a passengerside of the vehicle 100 and at least one duct through which cooled airflows to a driver side of the vehicle 100.

When the second evaporator control valve 248 is open, refrigerant may beexpanded to vapor form by a second expansion valve 272 and provided to asecond evaporator HEX 276. The second expansion valve 272 may include aTXV or may be an EXV. The second evaporator HEX 276 provides cooled airto the living portion 131 of the cooled space 128. More specifically,the vapor refrigerant within the second evaporator HEX 276 transfersheat away (i.e., absorbs heat) from air passing through the secondevaporator HEX 276. The cooled air flows from the second evaporator HEX276 to the living portion 131 of the vehicle 100 via second HVAC ducts278. The second HVAC ducts 278 include at least one duct through whichcooled air flows to a passenger side of the vehicle 100 and at least oneduct through which cooled air flows to a driver side of the vehicle 100.

A first blower 280 draws air from the cooled space 128 and/or fromoutside of the vehicle 100. When on, the first blower 280 increasesairflow over, around, and/or through the first evaporator HEX 268 toincrease the rate of heat transfer away from (i.e., cooling of) the airflowing through the first evaporator HEX 268 and to the cooled space128.

A second blower 282 draws air from the cooled space 128 and/or fromoutside of the vehicle 100. When on, the second blower 282 increasesairflow over, around, and/or through the second evaporator HEX 276 toincrease the rate of heat transfer away from (i.e., cooling of) the airflowing through the second evaporator HEX 276 and to the cooled space128. Refrigerant from the first evaporator HEX 268 and the secondevaporator HEX 276 flows back to the compressor 204 for a next cycle.

The control module 260 may control the speed of the first blower 280 andthe speed of the second blower 282 as discussed further below. Forexample, the control module 260 may control application of power toelectric motors of the first and second blowers 280 and 282 from thebattery pack 120 based on respective speed commands. Based on therespective speed commands, the control module 260 may generate AC power(e.g., single-phase or three-phase) from the power output of the batterypack 120 and apply the AC power to the electric motor 216. The controlmodule 260 may set one or more characteristics of the AC power based onthe respective speed commands, such as frequency, voltage, and/orcurrent. The control module 260 may, for example, may determine PWM dutycycles to apply to switches of the drive 256 to generate AC powershaving the characteristics.

The control module 260 may set the speed commands to a plurality ofdifferent possible speeds for variable speed operation of the first andsecond blowers 280 and 282. While the example of the control module 260applying power to the first and second blowers 280 and 282 is provided,another module or the drive 256 may apply power to the first and secondblowers 280 and 282.

Regarding active cooling of the drive 256, a damper door 284 may beimplemented to allow or block airflow from the second blower 282 to ahousing that houses the drive 256. For example, when the damper door 284is open, cool air from the second evaporator HEX 276 or cool air fromthe second HVAC ducts 278 may travel to the cooled space 128 and intothe housing of the drive 256 to cool the drive 256. When the damper door284 is closed, the damper door 284 may block airflow to the housing (andtherefore the drive 256). While the example of the damper door 284 isprovided, another suitable actuator may be used to allow/prevent airflowto the drive 256. Curved lines in FIG. 3 are illustrative of air flow.

The air conditioning system 124 may also include a compressor pressureregulator (CPR) valve that regulates pressure of refrigerant input tothe compressor 204 via the suction line. For example, the CPR valve maybe closed to limit pressure into the compressor 204 during startup ofthe compressor 204. The CPR valve may be an electronically controlledvalve (e.g., a stepper motor or solenoid valve), a mechanical valve, oranother suitable type of valve. In various implementations, the CPRvalve may be omitted.

FIG. 4 includes a functional block diagram of an example systemincluding the control module 260, various sensors of the vehicle 100,and various actuators of the vehicle 100. The control module 260receives various measured parameters and indications from sensors of thevehicle 100. The control module 260 controls actuators of the airconditioning system 124 of the vehicle 100. As an example, the controlmodule 260 may be an iPRO series control module (e.g., 100 series, 200series, 4 DIN series, 10 DIN series) by Dixell S.r.I., located in Pieved′Alpago (BL) Italy. One example is an iPRO IPG115D control module,however, the control module 260 may be another suitable type of controlmodule.

An ignition sensor 304 indicates whether an ignition system of thevehicle 100 is ON or OFF. A driver may turn the ignition system of thevehicle 100 ON and start the engine 104, for example, by actuating anignition key, button, or switch. The ignition system being ON indicatesthat the engine 104 is ON and combusting air and fuel. A driver may turnthe ignition system of the vehicle 100 OFF and shut down the engine 104,for example, by actuating the ignition key, button, or switch. Theignition system of being OFF indicates that the engine 104 is OFF andnot combusting and air fuel.

A discharge line temperature (DLT) sensor 308 measures a temperature ofrefrigerant output by the compressor 204 (e.g., in the discharge line).The temperature of refrigerant output by the compressor 204 can bereferred to as discharge line temperature or DLT. The discharge linetemperature may be directly provided to the control module 260.Alternatively, the discharge line temperature may be provided to thedrive 256 and the drive 256 may communicate the discharge linetemperature to the control module 260.

A liquid line temperature sensor 312 measures a temperature of liquidrefrigerant output from the condenser HEX 212 (e.g., in the liquidline). The temperature of refrigerant output by the condenser HEX 212can be referred to as liquid line temperature. While one examplelocation of the liquid line temperature sensor 312 is shown in FIG. 3,the liquid line temperature sensor 312 may be located at anotherlocation where liquid refrigerant is present in the refrigerant pathfrom the condenser HEX 212 to the second evaporator HEX 276 and thefirst evaporator HEX 268.

A liquid line pressure sensor 316 measures a pressure of liquidrefrigerant output from the condenser HEX 212 (e.g., in the liquidline). The pressure of refrigerant output by the condenser HEX 212 canbe referred to as liquid line pressure. While one example location ofthe liquid line pressure sensor 316 is shown in FIG. 3, the liquid linepressure sensor 316 may be located at another location where liquidrefrigerant is present in the refrigerant path from the condenser HEX212 to the second evaporator HEX 276 and the first evaporator HEX 268.

A suction pressure sensor 320 measures a pressure of refrigerant inputto the compressor 204 (e.g., in the suction line). The pressure ofrefrigerant input to the compressor 204 can be referred to as suctionpressure.

A suction temperature sensor 324 measures a temperature of refrigerantinput to the compressor 204 (e.g., in the suction line). The temperatureof refrigerant input to the compressor 204 can be referred to as suctiontemperature.

A first air temperature sensor 328 measures a temperature of air in thedriving portion 129 of the cooled space 128. For example, the first airtemperature sensor 328 may measure a temperature of air input to thefirst evaporator HEX 268. The temperature of air in the driving portion129 may be referred to as a driving portion temperature or a first spacetemperature (Space 1 temp).

A second air temperature sensor 332 measures a temperature of air in theliving portion 131 of the cooled space 128. For example, the second airtemperature sensor 332 may measure a temperature of air input to thesecond evaporator HEX 276. The temperature of air in the living portion131 may be referred to as a living portion temperature or a second spacetemperature (Space 2 temp).

A first evaporator temperature sensor 336 measures a temperature of thefirst evaporator HEX 268. For example, the first evaporator temperaturesensor 336 may measure the temperature of the first evaporator HEX 268at or near a midpoint of refrigerant flow through the first evaporatorHEX 268. The temperature of the first evaporator HEX 268 can be referredto as a first evaporator temperature.

A second evaporator temperature sensor 340 measures a temperature of thesecond evaporator HEX 276. For example, the second evaporatortemperature sensor 340 may measure the temperature of the secondevaporator HEX 276 at or near a midpoint of refrigerant flow through thesecond evaporator HEX 276. The temperature of the second evaporator HEX276 can be referred to as a second evaporator temperature.

A first blower speed input 344 adjusts a first blower speed command ofthe first blower 280 based on user interaction (e.g., actuation,touching, etc.) with one or user input devices. For example, the firstblower speed input 344 may increment and decrement the first blowerspeed command for the first blower 280 based on user input with the oneor more user input devices. A second blower speed input 348 adjusts asecond blower speed command of the second blower 282 based on userinteraction (e.g., actuation, touching, etc.) with one or user inputdevices. For example, the second blower speed input 348 may incrementand decrement the second blower speed command for the second blower 282based on user input with the one or more user input devices. Examples ofuser input devices include one or more buttons, switches, and/ortouchscreen displays.

A HVAC mode sensor 352 indicates a HVAC mode requested for the cooledspace 128. The HVAC mode may be, for example, heat, A/C, maximum A/C, orOFF. The HVAC mode sensor 352 may indicate the HVAC mode based on userinteraction (e.g., actuation, touching, etc.) with one or more inputdevices, such as one or more buttons, switches, and/or a touchscreendisplay. In various implementations, the HVAC mode may be provided byanother control module of the vehicle 100.

A battery sensor 356 measures characteristics of a battery of thebattery pack 120, such as voltage, current flow, temperature, and/orstate of charge. In various implementations, a voltage sensor, a currentsensor, and/or a temperature sensor may be provided with each battery ofthe battery pack 120. The battery sensor 356 may determine a state ofcharge (SOC) of the battery pack 120 based on one or more of themeasured parameters.

One or more power sensors 360 measure power parameters of the drive 256.For example, a voltage sensor may measure a voltage input to the drive256. A current sensor may measure a current flow to the drive 256. Apower sensor may measure a power consumption of the drive 256. Invarious implementations, current and power sensors may be omitted, andthe drive 256 may determine one or more currents and/or powerconsumption. In various implementations, the drive 256 may communicatethe power consumption to the control module 260. The drive 256 oranother module may determine the power consumption of the drive 256based on one or more measured parameters (e.g., voltage input to thedrive 256*current flow to the drive 256) and/or one or more otherparameters (e.g., current flow to the drive 256 and a resistance of thedrive 256).

A drive temperature sensor 364 measures a temperature at a location onthe drive 256. A temperature of the drive 256 may be referred to as adrive temperature. In various implementations, the drive temperaturesensor 364 may be implemented in the drive 256, and the drive 256 maycommunicate the drive temperature to the control module 260. Inimplementations, multiple drive temperature sensors may measuretemperatures at different locations on the drive 256. In the example ofthe multiple drive temperature sensors, a highest (largest/hottest) oneof the measured temperatures may be used as the drive temperature.Communication between the drive 256 and the control module 260 may beperformed, for example, according to the MODBUS or CANBUS protocol.

Sensors described herein may be analog sensors or digital sensors. Inthe case of an analog sensor, the analog signal generated by the sensormay be sampled and digitized (e.g., by the control module 260, the drive256, or another control module) to generate digital values,respectively, corresponding to the measurements of the sensor. Invarious implementations, the vehicle 100 may include a combination ofanalog sensors and digital sensors. For example, the ignition sensor 304and the HVAC mode sensor 352 may be digital sensors. The liquid linepressure sensor 316, the suction pressure sensor 320, the liquid linetemperature sensor 312, the suction temperature sensor 324, the firstevaporator temperature sensor 336, the second evaporator temperaturesensor 340, the first air temperature sensor 328, the second airtemperature sensor 332, and the first and second blower speed inputs 344and 348 may be analog sensors/devices.

As discussed further below, the control module 260 controls actuators ofthe air conditioning system 124 based on various measured parameters,indications, setpoints, and other parameters.

For example, the control module 260 may control a speed of the electricmotor 216 of the compressor 204 via the drive 256. The control module260 may also control the condenser fan(s) 220. For example, one or morerelays (R) 222 may be connected between the battery pack 120 and thecondenser fan(s). While the example of relays is provided, anothersuitable type of switching device may be used. The control module 260may control switching of the relay(s) 222 to control the speed of thecondenser fan(s) 220. For example, the control module 260 may controlthe speed of a condenser fan using pulse width modulation (PWM) oranalog (e.g., 0-10 or 0-5 volts DC) control of a relay or an integratedfan control module. Increasing the on period of the PWM signal or theanalog voltage applied to the integrated fan control module or relayincreases the speed of the condenser fan. Conversely, decreasing the onperiod of the PWM signal or the analog voltage applied to the integratedfan control module or relay decreases the speed of the condenser fan.

One or more of the condenser fan(s) 220 may be variable speed and/or oneor more of the condenser fan(s) 220 may be fixed speed. For example, thecondenser fan(s) 220 may include one fixed speed fan and one variablespeed fan. For a fixed speed condenser fan, when the fan is to be ON,the control module 260 closes the associated relay and maintains therelay closed. For a variable speed fan, the control module 260 maydetermine a speed command and apply a PWM signal or analog voltage tothe associated relay or integrated fan control module based on the speedcommand. The control module 260 may determine the ON period of the PWMsignal or the analog voltage to apply, for example, using one of alookup table and an equation that relates speed commands to on periodsof PWM signals or analog voltages.

The control module 260 may also control the first evaporator controlvalve 244. For example, the control module 260 may control the firstevaporator control valve 244 to be open to enable refrigerant flowthrough the first evaporator HEX 268 or closed to disable refrigerantflow through the first evaporator HEX 268. In the example of the firstexpansion valve 264 being an EXV, the control module 260 may controlopening of the first expansion valve 264.

The control module 260 may also control the second evaporator controlvalve 248. For example, the control module 260 may control the secondevaporator control valve 248 to be open to enable refrigerant flowthrough the second evaporator HEX 276 or closed to disable refrigerantflow through the second evaporator HEX 276. In the example of the secondexpansion valve 272 being an EXV, the control module 260 may controlopening of the second expansion valve 272.

The control module 260 may receive a signal that indicates whether theHPCO 262 has tripped (open circuited). The control module 260 may takeone or more remedial actions when the HPCO 262 has tripped, such asclosing one, more than one, or all of the above mentioned valves and/orturning OFF one, more than one, or all of the above mentioned fans. Thecontrol module 260 may generate an output signal indicating that theHPCO 262 has tripped when the discharge pressure of the compressor 204is greater than a predetermined pressure. The control module 260 mayenable operation of the air conditioning system 124 after the HPCO 262closes in response to the discharge pressure falling below than thepredetermined pressure. In various implementations, the control module260 may also require that one or more operating conditions be satisfiedbefore enabling operation of the air conditioning system 124 after theHPCO 262 closes.

The control module 260 may control the speeds of the first and secondblowers 280 and 282. The first and second blowers 280 and 282 arevariable speed blowers, and the control module 260 may determine firstand second speed commands for the first and second blowers 280 and 282and control the application of power to the first and second blowers 280and 282 based on the first and second speed commands, respectively.

FIG. 5 is a functional block diagram of an example implementation of thecontrol module 260. The control module 260 may include a blower speedmodule 404 that controls the speeds of the first and second blowers 280and 282. Generally speaking, as the speed of a blower increases, coolingprovided by the blower also increases and vice versa.

The blower speed module 404 controls the speeds of the first and secondblowers 280 and 282 based on the first and second blower speed commandsfor the first and second blowers 280 and 282, respectively. For example,based on the first and second blower speed commands, the blower speedmodule 404 may generate respective power for the first and secondblowers 280 and 282 from the power output of the battery pack 120 andapply the respective power to the first and second blowers 280 and 282.

A valve control module 408 controls actuation of the first and secondevaporator control valves 244 and 248. More specifically, the valvecontrol module 408 opens and closes the first evaporator control valve244 and opens and closes the second evaporator control valve 248. Thevalve control module 408 determines whether to open or close the firstevaporator control valve 244 and determines whether to open or close thesecond evaporator control valve 248 as discussed further below.

A damper control module 412 controls actuation of the damper door 284.More specifically, the damper control module 412 opens and closes thedamper door 284. The damper control module 412 determines whether toopen or close the damper door 284 as discussed further below.

A condenser control module 416 controls the speed of the electric motor216 of the compressor 204 based on a compressor speed command. Generallyspeaking, output of the compressor 204 increases as the speed of theelectric motor 216 increases, and vice versa. The condenser controlmodule 416 sets the compressor speed command as discussed further below.Based on the compressor speed command, the drive 256 generates AC powerfrom the power output of the battery pack 120 and applies the AC powerto the electric motor 216 of the compressor 204. In variousimplementations, the compressor control module 416 may generate the ACpower based on the compressor speed command and apply the AC power tothe electric motor 216.

The condenser control module 416 controls the speed of electric motor(s)of the condenser fan(s) 220 based on a condenser fan speed command.Generally speaking, airflow through the condenser HEX 212 increases asthe speed of the electric motor of the condenser fan(s) 220 increases,and vice versa. The condenser control module 416 sets the condenser fanspeed command. The condenser control module 416 controls switching ofthe relay(s) 222 (and therefore the application of power) based on thecondenser fan speed command. For example, for a fixed speed condenserfan, the condenser control module 416 may maintain an associated relayclosed while the condenser fan speed command is greater than zero andopen the associated relay when the condenser fan speed command is zero.For a variable speed condenser fan, the condenser control module 416 mayswitch an associated relay open and closed using a PWM signal having itson period (or an analog voltage) set based on the condenser fan speedcommand. The condenser control module 416 may increase the on period ofa PWM signal or an analog voltage as the condenser fan speed commandincreases and vice versa.

The condenser control module 416 sets the compressor speed command basedon a mathematical function of an initial compressor speed command and anadjustment value. For example, the condenser control module 416 may setthe compressor speed command based on a mathematical product of theinitial compressor speed command and the adjustment value (i.e.,compressor speed command=initial compressor speed command*adjustmentvalue). In this example, the adjustment value may be a value between 0.0(corresponding to 0 percent) and 1.0 (corresponding to 100 percent).Values greater than 1.0, however, can also be used. While the example ofmultiplying the initial compressor speed command with the adjustmentvalue will be discussed herein, another suitable mathematical functioncan be used, such as a sum of the initial compressor speed command andthe adjustment value.

FIG. 6 includes a flowchart depicting an example method of controllingthe speed of the compressor 204 for pulldown while maximizing efficiencyof the air conditioning system 124 and preventing freezing at the firstevaporator HEX 268. Control begins with 504 where the condenser controlmodule 416 determines whether the engine 104 is on (e.g., the ignitionsystem is ON), the first blower 280 is on (e.g., the first blower speedcommand is greater than zero), the HVAC mode has transitioned to an A/Cmode (e.g., A/C or maximum A/C), and the first evaporator temperature isgreater than the maximum temperature of the predetermined temperaturerange. Under these circumstances, it is likely that cooling of thedriving portion 129 will primarily be desired. Cooling of the livingportion 131 may be secondary.

The predetermined temperature range is bounded by a minimum temperatureand the maximum temperature. The minimum temperature may be apredetermined amount less than a predetermined setpoint temperature, andthe maximum temperature may be the predetermined amount greater than thepredetermined setpoint temperature.

The predetermined setpoint temperature may be calibratable and is set togreater than the freezing point temperature of water. For example, thepredetermined setpoint temperature may be set to 36 degrees Fahrenheitor another suitable temperature that is greater than the freezing pointtemperature of water.

The predetermined amount may be calibratable and is set to less than adifference between the predetermined setpoint temperature and thefreezing point temperature of water such that the minimum temperature isalso greater than the freezing point temperature of water. For exampleonly, the predetermined amount may be 2 degrees Fahrenheit or anothersuitable amount. In various implementations, the minimum and maximumtemperatures may not be centered with respect to the predeterminedsetpoint temperature.

If 504 is false, control may end. While control is shown and discussedas ending, control may return to 504. If 504 is true, the condensercontrol module 416 sets the initial compressor speed command to a firstpredetermined maximum speed of the compressor 204 at 508. The firstpredetermined maximum speed may be calibratable and may be set to amaximum speed of the compressor 204 for use while the engine 104 is ON.For example only, the first predetermined maximum speed may beapproximately 7000 revolutions per minute (RPM) or another suitablespeed. Also at 508, the valve control module 408 opens the firstevaporator control valve 244 and opens the second evaporator controlvalve 248. In various implementations, the valve control module 408 mayopen the first and second evaporator control valves 244 and 248 beforethe condenser control module 416 turns on the compressor 204. Operatingthe compressor 204 at the first predetermined maximum speed cools thefirst evaporator HEX 268 and the second evaporator HEX 276 (andtherefore the driving and living portions 129 and 131) as quickly aspossible. Because the engine 104 is ON, the battery pack 120 can berecharged as power is drawn from the battery pack 120 for operation ofthe air conditioning system 124. Control continues with 512.

At 512, the condenser control module 416 determines whether the firstevaporator temperature is less than the minimum temperature of thepredetermined temperature range.

If 512 is true, pulldown is complete, the valve control module 408 mayclose the second evaporator control valve 248, and control transfers to528, which is discussed further below. In various implementations, thevalve control module 408 may leave the second evaporator control valve248 open. If 512 is false, control continues with 516. At 516, thecondenser control module 416 determines the adjustment value based on atleast one of the discharge pressure, the power consumption of thecompressor 204, and the suction pressure. For example, the condensercontrol module 416 may determine the adjustment value using one of alookup table and an equation that relates discharge pressures toadjustment values.

FIG. 7 includes an example graph of adjustment values as a function ofdischarge pressure. Generally speaking, the condenser control module 416may set the adjustment value to a predetermined maximum value when thedischarge pressure is less than or equal to a predetermined minimumdischarge pressure. The condenser control module 416 may set theadjustment value to a predetermined minimum value (e.g., 0.75) when thedischarge pressure is greater than or equal to a predetermined maximumdischarge pressure. The condenser control module 416 may decrease theadjustment value toward the predetermined minimum value as the dischargepressure increases between the predetermined minimum and maximumdischarge pressures. The predetermined maximum value may be calibratableand may be set to 1.0 in the example of multiplication of the initialcompressor speed command with the adjustment value.

Additionally or alternatively to the use of the discharge pressure, thecondenser control module 416 may determine the adjustment value usingone of a lookup table and an equation that relates power consumptions(e.g., in Watts (W) or kW) to adjustment values. FIG. 8 includes anexample graph of adjustment values as a function of power consumption.Generally speaking, the condenser control module 416 may set theadjustment value to the predetermined maximum value when the powerconsumption is less than or equal to a predetermined minimum powerconsumption. The condenser control module 416 may set the adjustmentvalue to a predetermined minimum value (e.g., 0.9) when the powerconsumption is greater than or equal to a predetermined maximum powerconsumption. The condenser control module 416 may decrease theadjustment value toward the predetermined minimum value as the powerconsumption increases between the predetermined minimum and maximumpower consumptions. The predetermined minimum value in this example maybe less than the predetermined minimum value associated with dischargepressure.

Additionally or alternatively to the use of the discharge pressureand/or the power consumption, the condenser control module 416 maydetermine the adjustment value using one of a lookup table and anequation that relates suction pressures to adjustment values. An exampleinvolving use of suction pressure is discussed further below.

In various implementations, the condenser control module 416 maydetermine the adjustment value based on two or all of the dischargepressure, the power consumption, and the suction pressure. For example,the condenser control module 416 may determine a first adjustment valuebased on the discharge pressure as discussed above. The condensercontrol module 416 may also determine a second adjustment value based onthe power consumption as also discussed above. The condenser controlmodule 416 may also determine a third adjustment value based on thesuction pressure as also discussed above. The condenser control module416 may determine the adjustment value based on the first, second, andthird adjustment values. For example, the condenser control module 416may set the adjustment value based on or equal to the lesser one of thefirst, second, and third adjustment values.

The condenser control module 416 determines the compressor speed commandbased on the initial compressor speed command and the adjustment value.For example, the condenser control module 416 may set the compressorspeed command based on or equal to the initial compressor speed commandmultiplied by the adjustment value.

At 520, the condenser control module 416 may determine the condenser fanspeed command. The condenser control module 416 may determine thecondenser fan speed command, for example, using a lookup table or anequation that relates at least one of discharge pressures, powerconsumptions, and compressor speeds to condenser fan speed commands. Invarious implementations, 520 may be omitted and the condenser controlmodule 416 may set the condenser fan speed command to a predeterminedspeed.

At 524, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command and controls thespeed of the condenser fan(s) 220 based on the condenser fan speedcommand. More specifically, the drive 256 may generate AC power for theelectric motor 216 from the power output by the battery pack 120 andapply the AC power to the electric motor 216 of the compressor 204 toadjust the speed of the electric motor 216 toward or to the compressorspeed command. The condenser control module 416 also determines the onperiod of a PWM signal or an analog voltage based on the condenser fanspeed command and switches an associated relay or integrated fan controlmodule of a variable speed condenser fan using the PWM signal or theanalog voltage. If the condenser fan speed command is greater than zero,the condenser control module 416 may close the relay of an associatedfixed speed condenser fan. Control returns to 512. The blower speedmodule 404 also controls the speeds of the first and second blowers 280and 282 based on the first and second blower speed commands for thefirst and second blowers 280 and 282, respectively. For example, basedon the first and second blower speed commands, the blower speed module404 may generate respective power for the first and second blowers 280and 282 from the power output of the battery pack 120 and apply therespective power to the first and second blowers 280 and 282.

At 528, the control module 260 controls one or more actuators of the airconditioning system 124 to maintain the first evaporator temperature atapproximately the predetermined temperature setpoint. This preventsfreezing at the first evaporator HEX 268. For example, as discussedfurther below, the condenser control module 416 may control the speed ofthe compressor 204 based on the first evaporator temperature and/or thesuction pressure to maintain the first evaporator temperature atapproximately the predetermined temperature setpoint. Additionally oralternatively, the condenser control module 416 may control the speed ofthe condenser fan(s) 220 to maintain the first evaporator temperature atapproximately the predetermined temperature setpoint. Additionally oralternatively, the valve control module 408 may control opening/closingof the first and/or second evaporator control valves 244 and 248 tomaintain the first evaporator temperature at approximately thepredetermined temperature setpoint. When implemented, the valve controlmodule 408 may additionally or alternatively control actuation of thefirst expansion valve 264 and/or the second expansion valve 272 tomaintain the first evaporator temperature at approximately thepredetermined temperature setpoint.

FIGS. 9A and 9B include a flowchart depicting an example method ofcontrolling the speed of the compressor 204 based on the firstevaporator temperature for pulldown and preventing freezing at the firstevaporator HEX 268. Control begins with 504 and 508, as discussed above.Control continues with 612.

At 612, the condenser control module 416 determines whether the firstevaporator temperature is greater than the maximum temperature of thepredetermined temperature range. If 612 is false, control transfers to624, which is discussed further below. If 612 is true, control continueswith 616.

A first comparison module 420 may compare the first evaporatortemperature with the minimum temperature of the predeterminedtemperature range and the maximum temperature of the predeterminedtemperature range. The first comparison module 420 may generate a signalindicative of whether the first evaporator temperature is greater thanthe maximum temperature, less than the minimum temperature, or betweenthe minimum and maximum temperatures.

At 616, the condenser control module 416 sets the adjustment value tothe predetermined maximum value. As discussed above, the condensercontrol module 416 sets the compressor speed command based on theinitial compressor speed command and the adjustment value. The condensercontrol module 416 also resets a timer value tracked by a timer module424. The condenser control module 416 may reset the timer value, forexample, to zero.

At 620, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command. Controlreturns to 612.

At 624, the condenser control module 416 may determine whether the firstevaporator temperature is between the minimum and maximum temperaturesof the predetermined temperature range. If 624 is true, controlcontinues with 628. If 624 is false, control may transfer to 632. At628, the condenser control module 416 determines the adjustment valuebased on the suction pressure and resets the timer value. Control thencontinues with 620.

For example, the condenser control module 416 may determine theadjustment value using one of a lookup table and an equation thatrelates suction pressures to adjustment values. FIG. 10 includes anexample graph of adjustment values as a function of evaporatortemperature. Generally speaking, the condenser control module 416 mayset the adjustment value to the predetermined maximum value when thefirst evaporator temperature is greater than or equal to the maximumtemperature of the predetermined temperature range. The condensercontrol module 416 may set the adjustment value to a predeterminedminimum value (e.g., 0.8) when the first evaporator temperature is lessthan or equal to the minimum temperature of the predeterminedtemperature range. The condenser control module 416 may increase theadjustment value toward the predetermined maximum value as the firstevaporator temperature increases between the minimum and maximumtemperatures.

Referring again to FIG. 9A, at 632 (when the first evaporatortemperature is less than the minimum temperature of the predeterminedtemperature range) the condenser control module 416 may determinewhether the timer value is greater than a first predetermined timervalue. The first predetermined timer value corresponds to apredetermined period. The first predetermined timer value may becalibratable and may be set, for example, to correspond to approximately30 seconds or another suitable value. If 632 is false, the condensercontrol module 416 maintains the adjustment value (i.e., leaves theadjustment value unchanged from its last value) at 636 and incrementsthe timer by a predetermined increment value. Control then continueswith 620. At this time, the timer value therefore corresponds to theperiod since the first evaporator temperature became less than theminimum temperature of the predetermined temperature range. If 632 istrue, control transfers to 640 of FIG. 9B.

At 640, the condenser control module 416 sets the adjustment value to afirst predetermined adjustment value that is less than the predeterminedminimum value used when the suction pressure is less than or equal tothe predetermined minimum suction pressure. For example, in the exampleof the predetermined minimum value being 0.8, the first predeterminedadjustment value may be 0.75 or another suitable value that is less thanthe predetermined minimum value and greater than 0.0. The condensercontrol module 416 determines the compressor speed command based on theinitial compressor speed command and the adjustment value, as discussedabove. The condenser control module 416 also resets the timer value at640.

At 644, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command.

At 648, the condenser control module 416 determines whether the firstevaporator temperature is less than the minimum temperature of thepredetermined temperature range. If 648 is false, the condenser controlmodule 416 may reset the timer value and control may return to 612. If648 is true, control may continue with 652.

The condenser control module 416 maintains the adjustment value (i.e.,leaves the adjustment value unchanged from its last value) at 652 andincrements the timer value by the predetermined increment value. Controlthen continues with 654. At this time, the timer value thereforecorresponds to the period that the adjustment value has been set to thefirst predetermined adjustment value (due to the first evaporatortemperature being less than the minimum temperature of the predeterminetemperature range).

At 654, the condenser control module 416 may determine whether the timervalue is greater than a second predetermined timer value. The secondpredetermined timer value corresponds to a second predetermined period.The second predetermined timer value may be calibratable and may be set,for example, to correspond to approximately 1 minute or another suitablevalue. If 654 is false control returns to 644 to continue controllingthe compressor speed based on the first predetermined adjustment value.If 654 is true, control continues with 656.

At 656, the condenser control module 416 sets the adjustment value to apredetermined compressor stopping value. Based on the adjustment valuebeing set to the predetermined compressor stopping value, the condensercontrol module 416 sets the compressor speed command to 0. When thecompressor speed command is 0, the drive 256 does not apply power to theelectric motor 216, thereby stopping rotation of the electric motor 216and the compressor 204. The condenser control module 416 disables thecompressor 204 at this time to prevent freezing at the first evaporatorHEX 268. In the example of setting the compressor speed command to theinitial compressor speed command multiplied by the adjustment value, thepredetermined compressor stopping value is 0.0. Control may continuewith 660.

At 660, the condenser control module 416 may determine whether the firstevaporator temperature is greater than or equal to the predeterminedsetpoint temperature. If 660 is true, the condenser control module 416maintains the adjustment value at the predetermined compressor stoppingvalue at 664. This maintains the compressor 204 stopped. Control returnsto 660. In this way, the condenser control module 416 disables thecompressor 204 until the first evaporator temperature increases toprevent freezing at the first evaporator HEX 268. If 660 is true, thecondenser control module 416 may reset the timer value and control mayreturn to 612.

FIGS. 11A and 11B include a flowchart depicting an example method ofcontrolling the speed of the compressor 204 based on the firstevaporator temperature and the suction pressure for pulldown andpreventing freezing at the first evaporator HEX 268. Control begins with504 and 508, as discussed above. Control continues with 704.

At 704, the condenser control module 416 determines whether the firstevaporator temperature is less than the minimum temperature of thepredetermined temperature range. If 704 is true, control transfers to716, which is discussed further below. If 704 is false, controlcontinues with 708.

At 708, the condenser control module 416 sets the adjustment value tothe predetermined maximum value (e.g., 1.0). The condenser controlmodule 416 may also reset the timer value at 708. The condenser controlmodule 416 determines the compressor speed command based on theadjustment value and the initial compressor speed command as describedabove. At 712, the condenser control module 416 controls the speed ofthe compressor 204 based on the compressor speed command. Morespecifically, the drive 256 may generate AC power for the electric motor216 from the power output by the battery pack 120 and apply the AC powerto the electric motor 216 of the compressor 204 to adjust the speed ofthe electric motor 216 toward or to the compressor speed command.Control returns to 704.

At 716, the condenser control module 416 obtains the (present value ofthe) suction pressure and sets a predetermined setpoint suction pressurebased on or equal to the suction pressure. The condenser control module416 also determines a predetermined minimum suction pressure and apredetermined maximum suction pressure at 716. For example, thecondenser control module 416 may set the predetermined minimum suctionpressure based on or equal to the predetermined setpoint suctionpressure minus a second predetermined amount. The condenser controlmodule 416 may set the predetermined maximum suction pressure based onor equal to the predetermined setpoint suction pressure plus the secondpredetermined amount. The condenser control module 416 also resets thetimer value at 716.

At 720, the condenser control module 416 determines the adjustment valuebased on the suction pressure. For example, the condenser control module416 may determine the adjustment value using one of a lookup table andan equation that relates suction pressures to adjustment values. Thecondenser control module 416 determines the compressor speed commandbased on the initial compressor speed command and the adjustment value.

FIG. 12 includes an example graph of adjustment values as a function ofsuction pressure. Generally speaking, the condenser control module 416may set the adjustment value to the predetermined maximum value when thesuction pressure is greater than or equal to the predetermined maximumsuction pressure. The condenser control module 416 may set theadjustment value to a predetermined minimum value (e.g., 0.8) when thesuction pressure is less than or equal to the predetermined minimumsuction pressure. The condenser control module 416 may increase theadjustment value toward the predetermined maximum value as the suctionpressure increases between the predetermined minimum and maximum suctionpressures.

The predetermined minimum and maximum suction pressures bound apredetermined suction pressure range. For example only, the secondpredetermined amount may be calibratable and may be, for example,approximately 1-5 psig or another suitable amount. In variousimplementations, the predetermined minimum and maximum suction pressuresmay not be centered with respect to the predetermined setpoint suctionpressure.

Referring again to FIG. 11A, at 724, the condenser control module 416controls the speed of the compressor 204 based on the compressor speedcommand. More specifically, the drive 256 may generate AC power for theelectric motor 216 from the power output by the battery pack 120 andapply the AC power to the electric motor 216 of the compressor 204 toadjust the speed of the electric motor 216 toward or to the compressorspeed command.

At 728, the condenser control module 416 determines whether the firstevaporator temperature is less than the minimum temperature of thepredetermined temperature range. If 728 is false, control may return to708. If 728 is true, control may continue with 732.

At 732, the condenser control module 416 may determine whether the timervalue is greater than the first predetermined timer value. The firstpredetermined timer value corresponds to a predetermined period. Thefirst predetermined timer value may be calibratable and may be set, forexample, to correspond to approximately 30 seconds or another suitablevalue. If 732 is false, the condenser control module 416 increments thetimer value by the predetermined increment value at 736, and controlreturns to 720. At this time, the timer value therefore corresponds tothe period that the first evaporator temperature has been less thanminimum temperature of the predetermine temperature range during use ofthe suction pressure to determine the adjustment value. If 732 is true,control continues with 640-664, as discussed above in conjunction withthe example of FIGS. 9A and 9B. In the example of FIGS. 11A and 11B,control returns to 720 from 648 and 660. The setting of the adjustmentvalue to the first predetermined adjustment value (e.g., at 640) and thedisabling of the compressor 204 (e.g., at 656) prevent freezing at thefirst evaporator HEX 268.

In various implementations, the vehicle may also include a humiditysensor that measures a humidity of air within the cooled space 128. Thecontrol module 260 may adjust one or more operating parameters based onthe humidity. For example, in conjunction with the freezing preventionexamples, the control module 260 may adjust the speed of the compressor204 and/or a blower speed based on the humidity. Generally speaking, tohelp prevent freezing of an evaporator HEX, the control module 260 maydecrease the speed of the compressor 204 as the humidity increases andvice versa. Additionally or alternatively, to help prevent freezing ofan evaporator HEX, the control module 260 may increase the blower speedassociated with that evaporator HEX as humidity increases, and viceversa.

FIG. 13 includes a flowchart depicting an example method of controllingthe speed of the compressor 204 based on discharge pressure to limitpower consumption of the air conditioning system 124, maximizeefficiency of the air conditioning system 124, and improve comfort inthe driving portion 129. Control begins with 504-508, as discussedabove.

At 804, the condenser control module 416 determines the adjustment valuebased on the discharge pressure. For example, the condenser controlmodule 416 may determine the adjustment value using one of a lookuptable and an equation that relates discharge pressures to adjustmentvalues. The condenser control module 416 determines the compressor speedcommand based on the adjustment value and the initial compressor speedcommand as discussed above.

As discussed above, FIG. 7 includes an example graph of adjustmentvalues as a function of discharge pressure. Generally speaking, thecondenser control module 416 may set the adjustment value to thepredetermined maximum value (e.g., 1.0) when the discharge pressure isless than or equal to the predetermined minimum discharge pressure. Thecondenser control module 416 may set the adjustment value to thepredetermined minimum value (e.g., 0.75) when the discharge pressure isgreater than or equal to the predetermined maximum discharge pressure.The condenser control module 416 may decrease the adjustment valuetoward the predetermined minimum value as the discharge pressureincreases between the predetermined minimum and maximum dischargepressures.

At 808, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command. Controlmay then return to 804.

Controlling the speed of the compressor 204 based on the dischargepressure limits power consumption of the air conditioning system 124 bydecreasing the speed of the compressor 204 as the discharge pressureincreases. At a given speed, power consumption of the air conditioningsystem 124 increases as the discharge pressure increases. Decreasingpower consumption increases efficiency of the air conditioning system124 and may improve comfort in the driving portion 129 by preventing thecompressor 204 from being cycled OFF and ON.

FIG. 14 includes a flowchart depicting an example method of controllingthe speed of the compressor 204 based on power consumption of the airconditioning system 124 to maximize efficiency of the air conditioningsystem 124, limit power consumption of the air conditioning system 124,and improve comfort in the driving portion 129. Control begins with504-508, as discussed above.

At 904, the condenser control module 416 determines the adjustment valuebased on the power consumption of the air conditioning system 124. Forexample, the condenser control module 416 may determine the adjustmentvalue using one of a lookup table and an equation that relates powerconsumptions to adjustment values. The condenser control module 416determines the compressor speed command based on the adjustment valueand the initial compressor speed command as discussed above.

As discussed above, FIG. 8 includes an example graph of adjustmentvalues as a function of power consumption. Generally speaking, thecondenser control module 416 may set the adjustment value to thepredetermined maximum value (e.g., 1.0) when the power consumption isless than or equal to the predetermined minimum power consumption. Thecondenser control module 416 may set the adjustment value to thepredetermined minimum value (e.g., 0.9) when the power consumption isgreater than or equal to the predetermined maximum power consumption.The condenser control module 416 may decrease the adjustment valuetoward the predetermined minimum value as the power consumptionincreases between the predetermined minimum and maximum powerconsumptions.

At 908, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command. Controlmay then return to 904.

Controlling the speed of the compressor 204 based on the powerconsumption of the air conditioning system 124 may improve efficiency bydecreasing the speed of the compressor 204 as the power consumptionincreases. Decreasing power consumption may also improve comfort in thedriving portion 129 by preventing the compressor 204 from being cycledOFF and ON.

FIG. 15 includes a flowchart depicting an example method of controllingthe speed of the compressor 204 and the speed of the condenser fan(s)220 to limit power consumption of the air conditioning system 124,maximize efficiency, and improve comfort in the driving portion 129.Control begins with 504-508, as discussed above.

At 1004, the condenser control module 416 determines the compressorspeed command. The condenser control module 416 may determine thecompressor speed command based on the first evaporator temperature(e.g., in the example of FIGS. 9A and 9B), based on the first evaporatortemperature and the suction pressure (e.g., in the example of FIGS. 11Aand 11B), based on the discharge pressure (e.g., in the example of FIG.13), or based on the power consumption (e.g., in the example of FIG.14).

At 1008, the condenser control module 416 determines the condenser fanspeed command based on at least one of the power consumption, thedischarge pressure, and the compressor speed (e.g., the compressor speedcommand). The condenser control module 416 may determine the condenserfan speed using at least one of a lookup table and an equation thatrelates at least one of power consumptions, discharge pressures, andcompressor speeds to condenser fan speed commands.

FIG. 16 includes an example graph of condenser fan speed commands as afunction of power consumption for when the engine 104 is on. Generallyspeaking, when the engine 104 is on, the condenser control module 416may set the condenser fan speed command toward or to a predeterminedminimum speed when the power consumption is greater than or equal to apredetermined maximum power consumption. The condenser control module416 may set the condenser fan speed command to a predetermined maximumspeed when the power consumption is less than or equal to apredetermined minimum power consumption. The condenser control module416 may decrease the condenser fan speed command as the powerconsumption increases between the predetermined minimum and maximumpower consumptions.

FIG. 17 includes an example graph of condenser fan speed commands as afunction of discharge pressure for when the engine 104 is on. Generallyspeaking, when the engine 104 is on, the condenser control module 416may set the condenser fan speed command toward or to the predeterminedminimum speed when the discharge is greater than or equal to apredetermined maximum discharge pressure. The condenser control module416 may set the condenser fan speed command toward or to thepredetermined maximum speed when the discharge pressure is less than orequal to a predetermined minimum discharge pressure. The condensercontrol module 416 may decrease the condenser fan speed command as thedischarge pressure increases between the predetermined minimum andmaximum discharge pressures.

FIG. 18 includes an example graph of condenser fan speed commands as afunction of compressor speed for when the engine 104 is on. Generallyspeaking, when the engine 104 is on, the condenser control module 416may set the condenser fan speed command toward or to the predeterminedmaximum speed when the compressor speed is greater than or equal to apredetermined maximum compressor speed. The condenser control module 416may set the condenser fan speed command toward or to the predeterminedminimum speed when the compressor speed is less than or equal to thepredetermined minimum compressor speed. The condenser control module 416may increase the condenser fan speed command as the compressor speedincreases between the predetermined minimum and maximum compressorspeeds.

The condenser control module 416 may, for example, determine a firstpossible condenser fan speed command based on the power consumption,determine a second possible condenser fan speed command based on thedischarge pressure, and determine a third possible condenser fan speedcommand based on the compressor speed. In this example, the condensercontrol module 416 may set the condenser fan speed command to thehighest (greatest) one of the first, second, and third possiblecondenser fan speed commands. Selecting the highest one of the first,second, and third possible condenser fan speed commands may beprotectionary. Alternatively, the condenser control module 416 may setthe condenser fan speed command to the least (minimum) one of the first,second, and third possible condenser fan speed commands. Selecting theleast one of the first, second, and third possible condenser fan speedcommands may minimize power consumption of the condenser fan(s) 220.

In various implementations, the condenser control module 416 mayadditionally or alternatively determine the condenser fan speed commandbased on the suction pressure and/or the second blower speed. Forexample, while the engine 104 is on, the condenser control module 416may decrease the condenser fan speed command as the suction pressuredecreases and/or as the second blower speed decreases. The condensercontrol module 416 may increase the condenser fan speed command as thesuction pressure increases and/or as the second blower speed increases.

At 1012, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command and controls thespeed of the condenser fan(s) 220 based on the condenser fan speedcommand. More specifically, the drive 256 may generate AC power for theelectric motor 216 from the power output by the battery pack 120 andapply the AC power to the electric motor 216 of the compressor 204 toadjust the speed of the electric motor 216 toward or to the compressorspeed command. The condenser control module 416 also controls switchingof the relays 222 to control application of power to the condenserfan(s) 220 based on to the condenser fan speed command. Control returnsto 1004.

The examples of FIGS. 6, 9A-9B, and 11A-11B, and 13-15 are shown anddescribed based on the conditions of 504 remaining satisfied. If theengine 104 is turned off, the HVAC mode transitions to OFF or to heat,or the first blower 280 is shut down, the condenser control module 416may shut down the compressor 204 and control may end.

FIGS. 19A and 19B include a flowchart depicting an example method ofcontrolling the speed of the compressor 204 to manage the charge of thebattery pack 120 as long as possible while the engine 104 is off. Whenthe engine 104 is off, the electrical source 112 cannot charge thebattery pack 120. Operation of the air conditioning system 124 drawspower from the battery pack 120.

Control begins with 1104 where the condenser control module 416determines whether the engine 104 is OFF (e.g., the ignition system isOFF), the second blower 282 is on (e.g., the second blower speed commandis greater than zero), and the HVAC mode has transitioned to an A/C mode(e.g., A/C or maximum A/C). Under these circumstances, it is likely thatcooling of the living portion 131 will primarily be desired. If 1104 istrue, control continues with 1108. If 1104 is false, control may end.While control is shown and discussed as ending, control may return to1104.

At 1108, the condenser control module 416 sets the initial compressorspeed command to a second predetermined maximum speed of the compressor204. The second predetermined maximum speed may be calibratable, may beset to a maximum speed of the compressor 204 for use while the engine104 is OFF, and is less than the first predetermined maximum speeddiscussed above and greater than 0. For example only, the secondpredetermined maximum speed may be approximately 2000 RPM, 1400 RPM, oranother suitable speed. Also at 1108, the valve control module 408closes the first evaporator control valve 244 and opens the secondevaporator control valve 248. Operating the compressor 204 at the secondpredetermined maximum speed with the second evaporator control valve 248open cools the second evaporator HEX 276 (and therefore the livingportion 131). The condenser control module 416 also sets the adjustmentvalue to the predetermined maximum value (e.g., 1.0) at 1108. Thecondenser control module 416 determines the compressor speed commandbased on the adjustment value and the initial compressor speed commandas discussed above. The condenser control module 416 also resets thetimer value at 1108. Control continues with 1112.

At 1112, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command.

At 1116, the condenser control module 416 determines whether the timervalue is greater than a third predetermined value. The thirdpredetermined timer value corresponds to a predetermined period. Thethird predetermined timer value may be calibratable and may be set, forexample, to correspond to approximately 1 minute or another suitablevalue sufficient for current to reach steady-state. If 1116 is false,the condenser control module 416 increments the timer by thepredetermined increment value at 1120, and control returns to 1112 tocontinue operating the compressor 204 based on the second predeterminedmaximum speed. If 1116 is true, control continues with 1124.

At 1124, the condenser control module 416 determines the (present valueof the) compressor current. At 1128, the condenser control module 416may determine whether the compressor current is greater than apredetermined current. If 1128 is true, an expected load of the airconditioning system 124 on the battery pack 120 may be relatively highunder the current operating conditions, and control may continue with1144 (FIG. 19B), which is discussed further below. If 1128 is false, theexpected load of the air conditioning system 124 on the battery pack 120may be relatively low under the current operating conditions, andcontrol may transfer to 1132. The predetermined current may becalibratable and may be set based on the amp-hour rating of the batterypack 120.

A second comparison module 428 (FIG. 5) may compare the compressorcurrent with the predetermined current. The second comparison module 428may generate a signal indicative of whether the compressor current isgreater than the predetermined current or not.

At 1132, the condenser control module 416 determines the adjustmentvalue based on the second space temperature. The condenser controlmodule 416 may determine the adjustment value, for example, using one ofa lookup table and an equation that relates second space temperatures toadjustment values. As discussed above, the condenser control module 416determines the compressor speed command based on the initial compressorspeed command and the adjustment value.

FIG. 20 includes an example graph of adjustment values as a function ofsecond space temperatures. Generally speaking, when the engine 104 isoff, the condenser control module 416 may set the adjustment value tothe predetermined maximum value (e.g., 1.0) when the second spacetemperature is equal to a predetermined maximum second spacetemperature. The condenser control module 416 may set the adjustmentvalue to a predetermined minimum value (e.g., 0.33) when the secondspace temperature is equal to a predetermined minimum second spacetemperature. The condenser control module 416 may increase theadjustment value toward the predetermined maximum value as the secondspace temperature increases between the predetermined minimum andmaximum second space temperatures.

Referring back to FIG. 19A, the condenser control module 416 controlsthe speed of the compressor 204 based on the compressor speed command at1136. More specifically, the drive 256 may generate AC power for theelectric motor 216 from the power output by the battery pack 120 andapply the AC power to the electric motor 216 of the compressor 204 toadjust the speed of the electric motor 216 toward or to the compressorspeed command.

At 1140, the condenser control module 416 determines whether the voltageof the battery pack 120 is less than a predetermined voltage. Thepredetermined voltage may be calibratable and is set to less than therated voltage of the battery pack 120, such as approximately 46 V oranother suitable voltage. If 1140 is true, control transfers to 1144(FIG. 19B). If 1140 is false, control returns to 1132.

A third comparison module 432 (FIG. 5) may compare the voltage of thebattery pack 120 with the predetermined voltage. The third comparisonmodule 432 may generate a signal indicative of whether the voltage lessthan the predetermined voltage or not.

At 1144 (FIG. 19B), the condenser control module 416 sets the initialcompressor speed command to a third predetermined maximum speed of thecompressor 204. The third predetermined maximum speed may becalibratable and is less than the second predetermined maximum speeddiscussed above and greater than 0. For example only, the thirdpredetermined maximum speed may be approximately 1400 RPM or anothersuitable speed. Also at 1144, the condenser control module 416 also setsthe adjustment value to the predetermined maximum value (e.g., 1.0). Thecondenser control module 416 determines the compressor speed commandbased on the adjustment value and the initial compressor speed commandas discussed above.

At 1148, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command. More specifically,the drive 256 may generate AC power for the electric motor 216 from thepower output by the battery pack 120 and apply the AC power to theelectric motor 216 of the compressor 204 to adjust the speed of theelectric motor 216 toward or to the compressor speed command.

At 1152, the condenser control module 416 determines whether the secondspace temperature is less than a minimum temperature of a secondpredetermined temperature range. If 1152 is false, the condenser controlmodule 416 maintains the adjustment value at 1156, and control returnsto 1148 to continue operating the compressor 204 at the thirdpredetermined maximum speed. If 1152 is true, control continues to 1160.In this way, the condenser control module 416 cools the living portion131 until the temperature within the living portion 131 (represented bythe second space temperature) is less than the minimum temperature ofthe second predetermined temperature range.

The second predetermined temperature range is bounded by the minimumtemperature and a maximum temperature. The minimum temperature may be athird predetermined amount less than a second predetermined setpointtemperature, and the maximum temperature may be the third predeterminedamount greater than the second predetermined setpoint temperature.

The second predetermined setpoint temperature may be set, for example,based on user input regarding a desired temperature in the livingportion 131. The user may adjust (increase and decrease) the desiredtemperature via interaction with one or more user input devices.

The third predetermined amount may be calibratable. For example only,the third predetermined amount may be 4 degrees Fahrenheit or anothersuitable amount. In various implementations, the minimum and maximumtemperatures may not be centered with respect to the secondpredetermined setpoint temperature.

At 1160, the condenser control module 416 sets the adjustment value tothe predetermined compressor stopping value (e.g., 0.0). Based on theadjustment value being set to the predetermined compressor stoppingvalue, the condenser control module 416 sets the compressor speedcommand to 0. When the compressor speed command is 0, the drive 256 doesnot apply power to the electric motor 216, thereby stopping rotation ofthe electric motor 216 and the compressor 204. The condenser controlmodule 416 disables the compressor 204 at this time to stop powerconsumption from the battery pack 120.

At 1164, the condenser control module 416 may determine whether thesecond space temperature is greater than or equal to the maximumtemperature of the second predetermined temperature range. If 1164 isfalse, the condenser control module 416 maintains the adjustment valueat the predetermined compressor stopping value at 1172. This maintainsthe compressor 204 stopped. Control returns to 1164. In this way, thecondenser control module 416 disables the compressor 204 until thesecond space temperature increases to above the second predeterminedtemperature range to minimize power consumption from the battery pack120. If 1164 is true, the condenser control module 416 may set theadjustment value to 1 to resume operation of the compressor 204 at thethird predetermined maximum speed at 1168. Control returns to 1148 toagain cool the second space temperature to less than the minimumtemperature of the second predetermined temperature range.

FIG. 21 includes a flowchart depicting an example method of controllingthe speed of the compressor 204 to manage the charge of the battery pack120 while the engine 104 is off. When the engine 104 is off, theelectrical source 112 cannot charge the battery pack 120. Operation ofthe air conditioning system 124 draws power from the battery pack 120.

Control begins with 1104 where the condenser control module 416determines whether the engine 104 is OFF (e.g., the ignition system isOFF), the second blower 282 is on (e.g., the second blower speed commandis greater than zero), and the HVAC mode has transitioned to an A/C mode(e.g., A/C or maximum A/C). Under these circumstances, it is likely thatcooling of the living portion 131 will primarily be desired. If 1104 istrue, control continues with 1180. If 1104 is false, control may end.While control is shown and discussed as ending, control may return to1104.

At 1180, the valve control module 408 closes the first evaporatorcontrol valve 244 and opens the second evaporator control valve 248.Control continues with 1184. The condenser control module 416 determinesthe compressor speed command at 1184. The condenser control module 416may determine the compressor speed command, for example, as describedabove in conjunction with the examples of FIGS. 19A-19B. At 1188, thecondenser control module 416 determines the condenser fan speed command.

The condenser control module 416 determines the condenser fan speedcommand based on at least one of the power consumption, the dischargepressure, and the compressor speed (e.g., the compressor speed command).The condenser control module 416 may determine the condenser fan speedusing at least one of a lookup table and an equation that relates atleast one of power consumptions, discharge pressures, and compressorspeeds to condenser fan speed commands.

FIG. 22 includes an example graph of condenser fan speed commands as afunction of power consumption for when the engine 104 is off. Generallyspeaking, when the engine 104 is off, the condenser control module 416may set the condenser fan speed command toward or to a predeterminedmaximum speed when the power consumption is less than or equal to apredetermined minimum power consumption. The condenser control module416 may set the condenser fan speed command to a predetermined minimumspeed when the power consumption is greater than or equal to apredetermined maximum power consumption. The condenser control module416 may decrease the condenser fan speed command as the powerconsumption increases between the predetermined minimum and maximumpower consumptions.

FIG. 23 includes an example graph of condenser fan speed commands as afunction of discharge pressure for when the engine 104 is off. Generallyspeaking, when the engine 104 is off, the condenser control module 416may set the condenser fan speed command toward or to the predeterminedmaximum speed when the discharge is less than or equal to apredetermined minimum discharge pressure. The condenser control module416 may set the condenser fan speed command toward or to thepredetermined minimum speed when the discharge pressure is greater thanor equal to the predetermined maximum discharge pressure. The condensercontrol module 416 may decrease the condenser fan speed command as thedischarge pressure increases between the predetermined minimum andmaximum discharge pressures.

FIG. 24 includes an example graph of condenser fan speed commands as afunction of compressor speed for when the engine 104 is off. Generallyspeaking, when the engine 104 is off, the condenser control module 416may set the condenser fan speed command toward or to the predeterminedmaximum speed when the compressor speed is less than or equal to apredetermined minimum compressor speed. The condenser control module 416may set the condenser fan speed command toward or to the predeterminedminimum speed when the compressor speed is greater than or equal to thepredetermined maximum compressor speed. The condenser control module 416may decrease the condenser fan speed command when the compressor speedincreases.

The condenser control module 416 may, for example, determine a firstpossible condenser fan speed command based on the power consumption,determine a second possible condenser fan speed command based on thedischarge pressure, and determine a third possible condenser fan speedcommand based on the compressor speed. In this example, the condensercontrol module 416 may set the condenser fan speed command to thehighest (greatest) one of the first, second, and third possiblecondenser fan speed commands. Selecting the highest one of the first,second, and third possible condenser fan speed commands may beprotectionary. Alternatively, the condenser control module 416 may setthe condenser fan speed command to the least (minimum) one of the first,second, and third possible condenser fan speed commands. Selecting theleast one of the first, second, and third possible condenser fan speedcommands may minimize power consumption of the condenser fan(s) 220.

In various implementations, the condenser control module 416 mayadditionally or alternatively determine the condenser fan speed commandbased on the suction pressure and/or the second blower speed. Forexample, while the engine 104 is off, the condenser control module 416may decrease the condenser fan speed command as the suction pressureincreases and/or as the second blower speed decreases. The condensercontrol module 416 may increase the condenser fan speed command as thesuction pressure decreases and/or as the second blower speed increases.In various implementations, determination of the condenser fan speedcommand based on the discharge pressure while the engine 104 is off maybe omitted.

At 1192, the condenser control module 416 controls the speed of thecompressor 204 based on the compressor speed command and controls thespeed of the condenser fan(s) 220 based on the condenser fan speedcommand. More specifically, the drive 256 may generate AC power for theelectric motor 216 from the power output by the battery pack 120 andapply the AC power to the electric motor 216 of the compressor 204 toadjust the speed of the electric motor 216 toward or to the compressorspeed command. The condenser control module 416 also controls switchingof the relay(s) 222 based on the condenser fan speed command. Controlreturns to 1180.

The examples of FIGS. 19A-19B and FIG. 21 are shown and described basedon the conditions of 1104 remaining satisfied. If the engine 104 isturned on, the HVAC mode transitions to OFF or to heat or the secondblower 282 is shut down, the condenser control module 416 may shut downthe compressor 204 and control may end.

FIG. 25 includes a flowchart depicting an example method of controllingthe damper door 284 for cooling of the drive 256. FIG. 26A includes adiagram including an example implementation of the damper door 284, thesecond HVAC ducts 278, and airflow that can be used to cool the drive256.

Control may begin with 1204 where the damper control module 412determines whether the compressor 204 is ON. For example, the dampercontrol module 412 may determine whether the compressor speed command isgreater than zero. The damper control module 412 may also determinewhether the second blower 282 is on at 1204. As discussed above, thevalve control module 408 opens the second evaporator control valve 248before the compressor 204 is turned on when the second blower 282 is on.If 1204 is false (i.e., one or more of the above are false), the dampercontrol module 412 may close the damper door 284 at 1208, and controlmay return to 1204. In various implementations, the damper door 284 maybe normally closed (e.g., via a spring, etc.). If 1204 is true, controlcontinues with 1210.

At 1210, the damper control module 412 may determine whether the HVACmode is not set to the heating mode at 1204. If 1210 is true, the dampercontrol module 412 may close the damper door 284 at 1208, and controlmay return to 1204. If 1210 is false, control continues with 1212.

At 1212, the damper control module 412 determines whether the drivetemperature is greater than a predetermined drive temperature. If 1212is false, control transfers to 1208 and the damper control module 412may close the damper door 284 if the damper door 284 is not alreadyclosed. If 1212 is true, control continues with 1216. The predeterminedtemperature may be calibratable and may be a fixed value. A fourthcomparison module 436 (FIG. 5) may compare the drive temperature withthe predetermined drive temperature. The fourth comparison module 436may generate a signal indicative of whether the drive temperature isgreater than the predetermined drive temperature or not.

At 1216, when the drive temperature is greater than the predetermineddrive temperature, the damper control module 412 opens the damper door284. Opening the damper door 284, for example, to a fixed orproportional percentage allows cool air to flow from the second HVACducts 278 to the drive 256 and cool the drive 256. Generally speaking,efficiency of the drive 256 increases when the drive temperature iscooler. Cooler drive temperatures also increase reliability and life ofthe drive 256 and the components of the drive 256. Opening the damperdoor 284 when the drive temperature is greater than the predeterminedtemperature may also enable the use of less costly components for thedrive 256 (namely components having lower operating temperatureratings). This may decrease an overall cost of the drive 256. Controlmay return to 1204 after 1216.

FIG. 26B includes a diagram including an example implementation of adrive fan 1304 implemented to draw air from the passenger cabin (e.g.,131 and/or 129) and to push the air across the drive 256 to cool thedrive 256. For example, the drive fan 1304 may be mounted to a housing1308 of the drive 256. The housing 1308 may include apertures (e.g.,baffles or vents) that allow airflow out of the housing 1308. As shownin the example of FIG. 26B, the damper door 284 and the associatedconnecting ducts may be omitted.

A drive fan control module 1312 (FIG. 5) may control whether the drivefan 1304 is on or off, as discussed further below.

FIGS. 26C, 26D, and 26E include a diagram including an exampleimplementation including an actuator 1316 and the damper door 284. Theactuator 1316 actuates (e.g., linearly) the damper door 284 to allow thedrive fan 1304 to draw air from (a) only an evaporator HEX (e.g., thesecond evaporator hex 276), as depicted in FIG. 26C, (b) only thepassenger cabin (e.g., 131 and/or 129) as depicted in FIG. 2D, or acombination of the passenger cabin (e.g., 131 and/or 129) and theevaporator HEX as depicted in FIG. 26E. In the examples of FIGS. 26C,26D, and 26E, the drive fan 1304 may be, for example, mounted to thehousing 1308.

FIG. 27 includes a flowchart depicting an example method of controllingthe drive fan 1304 to minimize noise. While the example of controllingonly the drive fan 1304 will be discussed for purposes of simplicity,FIG. 27 is applicable to controlling only the second drive fan 1316 andto controlling both the drive fan 1304 and the second drive fan 1316.

Control begins when the drive fan 1304 is off and the engine 104 is off.If the engine 104 turns on, the example of FIG. 27 may end. At 1404, thedrive fan control module 1312 determines whether the drive temperatureis greater than a predetermined maximum drive temperature of apredetermined drive temperature range. If 1404 is false, the drive fancontrol module 1312 maintains the drive fan 1304 off at 1408, andcontrol returns to 1404. If 1404 is true, control continues with 1412.

The predetermined drive temperature range is bounded by thepredetermined maximum drive temperature and a predetermined minimumdrive temperature. The predetermined minimum drive temperature may be apredetermined amount less than a predetermined drive setpointtemperature, and the predetermined maximum drive temperature may be thepredetermined amount greater than the predetermined drive setpointtemperature.

The predetermined setpoint temperature may be calibratable and may beset to less than a lowest temperature rating of the components of thedrive 256. The predetermined amount may be calibratable and is set toless than a difference between the predetermined setpoint temperatureand the lowest temperature rating such that the predetermined maximumdrive temperature is also less than the lowest temperature rating. Forexample only, the predetermined amount may be 5 degrees Fahrenheit oranother suitable amount. In various implementations, the predeterminedminimum and maximum drive temperatures may not be centered with respectto the predetermined drive setpoint temperature.

At 1412, the drive fan control module 1312 turns on the drive fan 1304.The drive fan control module 1312 may operate the drive fan 1304 at afirst predetermined speed. Alternatively, the drive fan control module1312 may operate the drive fan 1304 based on a drive fan speed command.The drive fan control module 1312 may determine the drive fan speedcommand, for example, based on a rate of increase of the drivetemperature. The drive fan control module 1312 may determine the drivefan speed command, for example, using one of a function and a lookuptable that relates rates of increase of drive temperature to drive fanspeed command. Generally speaking, the drive fan speed command mayincrease as the rate of increase increases and vice versa. The drive fan1304 cools the drive 1304 when the drive fan 103 is on. Controlcontinues with 1416.

At 1416, the drive fan control module 1312 determines whether the drivetemperature is less than the predetermined minimum drive temperature ofthe predetermined drive temperature range. If 1416 is false, the drivefan control module 1312 returns to 1412 and maintains the drive fan 1304on. If 1416 is true, the drive fan control module 1312 turns the drivefan 1304 off at 1420, and control returns to 1404. The drive fan controlmodule 1312 may alternatively reduce the speed of the drive fan 1304 toa second predetermined speed that is less than the first predeterminedspeed at 1420. Controlling the drive fan 1304 as described aboveminimizes noise while the engine 104 is off.

While the example of control beginning when the drive fan 1304 is off isprovided, the present application is also applicable to controlbeginning when the drive fan 1304 is turned on or is already on. Whenthe drive fan 1304 is on, control begins with 1416.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

What is claimed is:
 1. An air conditioning system of a vehicle having aninternal combustion engine, comprising: an electric compressor; acondenser that is configured to receive refrigerant output by theelectric compressor and that transfers heat from the refrigerant withinthe condenser to air passing the condenser; a first control valve; afirst evaporator that is configured to receive refrigerant from thecondenser when the first control valve is open and that transfers heatfrom air passing the first evaporator to the refrigerant within thefirst evaporator; a first blower that is configured to blow air acrossthe first evaporator to a first section of a cabin of the vehicle; asecond control valve; a second evaporator that is configured to receiverefrigerant from the condenser when the second control valve is open andthat transfers heat from air passing the second evaporator to therefrigerant within the second evaporator; a second blower that isconfigured to blow air across the second evaporator to a second sectionof the cabin of the vehicle; and a control module that is configured toopen the first control valve and start operation of the electriccompressor when the internal combustion engine of the vehicle is on andthe first blower is blowing air across the first evaporator.
 2. The airconditioning system of claim 1 wherein the control module is furtherconfigured to open the second control valve when the internal combustionengine of the vehicle is on and the second blower is blowing air acrossthe second evaporator.
 3. The air conditioning system of claim 1 furthercomprising an inverter drive configured to apply power to the electriccompressor based on a compressor speed command from the control module,wherein the control module is configured to, when the internalcombustion engine of the vehicle is on and the first blower is blowingair across the first evaporator, set the compressor speed command to aspeed greater than zero based on a discharge pressure of the electriccompressor.
 4. The air conditioning system of claim 3 wherein thecontrol module is configured to: decrease the compressor speed commandas the discharge pressure increases; and increase the compressor speedcommand as the discharge pressure decreases.
 5. The air conditioningsystem of claim 3 wherein the control module is configured to determinethe compressor speed command based on the discharge pressure until atemperature of the first evaporator is less than a predeterminedtemperature, and wherein the predetermined temperature is greater thanthe freezing point temperature of water.
 6. The air conditioning systemof claim 1 further comprising an inverter drive configured to applypower to the electric compressor based on a compressor speed commandfrom the control module, wherein the control module is configured to,when the internal combustion engine of the vehicle is on and the firstblower is blowing air across the first evaporator, set the compressorspeed command to a speed greater than zero based on a present powerconsumption.
 7. The air conditioning system of claim 6 wherein thecontrol module is configured to: decrease the compressor speed commandas the power consumption increases; and increase the compressor speedcommand as the power consumption decreases.
 8. The air conditioningsystem of claim 6 wherein the control module is configured to determinethe compressor speed command based on the power consumption until atemperature of the first evaporator is less than a predeterminedtemperature, and wherein the predetermined temperature is greater thanthe freezing point temperature of water.
 9. The air conditioning systemof claim 1 further comprising an inverter drive configured to applypower to the electric compressor based on a compressor speed commandfrom the control module, wherein the control module is configured to,when the internal combustion engine of the vehicle is on and the firstblower is blowing air across the first evaporator, set the compressorspeed command to a speed greater than zero based on a discharge pressureof the electric compressor and a present power consumption.
 10. The airconditioning system of claim 9 wherein the control module is configuredto: decrease the compressor speed command when at least one of: thepower consumption increases; and the discharge pressure increases; andincrease the compressor speed command when at least one of: the powerconsumption decreases; and the discharge pressure decreases.
 11. An airconditioning control method for a vehicle having an internal combustionengine, comprising: determining whether the internal combustion engineof the vehicle is on; determining whether a first blower of the vehicleis blowing air across a first evaporator, wherein the first evaporatoris configured to receive refrigerant from a condenser when a firstcontrol valve is open and to transfer heat from air passing the firstevaporator to the refrigerant within the first evaporator, wherein thefirst blower is configured to blow air across the first evaporator to afirst section of a cabin of the vehicle, and wherein the condenser isconfigured to receive refrigerant output by an electric compressor andto transfer heat from the refrigerant within the condenser to airpassing the condenser; and when the internal combustion engine of thevehicle is on and the first blower is blowing air across the firstevaporator, opening the first control valve and starting operation ofthe electric compressor, wherein a second evaporator is configured toreceive refrigerant from the condenser when a second control valve isopen and to transfer heat from air passing the second evaporator to therefrigerant within the second evaporator, and wherein a second blower isconfigured to blow air across the second evaporator to a second sectionof the cabin of the vehicle.
 12. The air conditioning control method ofclaim 11 further comprising opening the second control valve when theinternal combustion engine of the vehicle is on and the second blower isblowing air across the second evaporator.
 13. The air conditioningcontrol method of claim 11 further comprising: applying power to theelectric compressor based on a compressor speed command; and when theinternal combustion engine of the vehicle is on and the first blower isblowing air across the first evaporator, setting the compressor speedcommand to a speed greater than zero based on a discharge pressure ofthe electric compressor.
 14. The air conditioning control method ofclaim 13 further comprising: decreasing the compressor speed command asthe discharge pressure increases; and increasing the compressor speedcommand as the discharge pressure decreases.
 15. The air conditioningcontrol method of claim 13 further comprising determining the compressorspeed command based on the discharge pressure until a temperature of thefirst evaporator is less than a predetermined temperature, wherein thepredetermined temperature is greater than the freezing point temperatureof water.
 16. The air conditioning control method of claim 11 furthercomprising: by an inverter drive, applying power to the electriccompressor based on a compressor speed command; and when the internalcombustion engine of the vehicle is on and the first blower is blowingair across the first evaporator, setting the compressor speed command toa speed greater than zero based on a present power consumption.
 17. Theair conditioning control method of claim 16 further comprising:decreasing the compressor speed command as the power consumptionincreases; and increasing the compressor speed command as the powerconsumption decreases.
 18. The air conditioning control method of claim16 further comprising determining the compressor speed command based onthe power consumption until a temperature of the first evaporator isless than a predetermined temperature, wherein the predeterminedtemperature is greater than the freezing point temperature of water. 19.The air conditioning control method of claim 11 further comprising: byan inverter drive, applying power to the electric compressor based on acompressor speed command; and when the internal combustion engine of thevehicle is on and the first blower is blowing air across the firstevaporator, setting the compressor speed command to a speed greater thanzero based on a discharge pressure of the electric compressor and apresent power consumption.
 20. The air conditioning control method ofclaim 19 further comprising: decreasing the compressor speed commandwhen at least one of: the power consumption increases; and the dischargepressure increases; and increasing the compressor speed command when atleast one of: the power consumption decreases; and the dischargepressure decreases.